Investigating the relationship between neuropsychiatric symptoms and cognition in mild cognitive impairment and Alzheimer’s disease patients undergoing an exercise‐primed transcranial direct current stimulation clinical trial (The EXPRESS Study)

Abstract

AbstractBackgroundNeuropsychiatric symptoms (NPS) are common features of Mild Cognitive Impairment (MCI) and Alzheimer’s disease (AD), and are associated with poorer cognition. Transcranial direct current stimulation (tDCS), a non‐invasive type of brain stimulation, has been investigated for the treatment of some NPS in a few small AD studies, but with negative results for apathy and depression. Priming the brain with an excitatory intervention, such as exercise, may elicit greater changes if applied prior to tDCS. Using data from an ongoing blinded study, we aimed to evaluate the relationship between NPS and cognition in MCI and mild AD.MethodMCI or mild AD participants were enrolled in a two‐week, randomized, blinded clinical trial investigating the effects of exercise‐primed tDCS for cognition using the Montreal Cognitive Assessment (MoCA). NPS were measured using the Neuropsychiatric Inventory (NPI) subscales. A Pearson’s correlation determined the relationship between NPI scores and the MoCA at baseline in patients who received exercise‐primed tDCS or tDCS alone. A repeated measures analysis of variance compared changes in NPI scores between the two treatment groups over time. As the study is ongoing, the treatment groups have been randomly coded as Group 1 and Group 2 to avoid unblinding.ResultAt baseline, participants (N=13) were 76.5±7.2 years of age, MoCA score= 20.9±3.6, 53% female, and 53% MCI. Nine (69.2%) participants reported having at least one NPS (NPI Score ≥ 1). Apathy (46.2%), sleep disturbances (38.5%), agitation (30.8%), and anxiety (30.8%) were the most prevalent NPS. At baseline, only anxiety was negatively correlated with MoCA scores (r=‐0.57, p=0.041; Figure 1). There were no significant differences between treatment groups on anxiety scores over time (F(1,10)= 2.4, p=0.16). However, after controlling for baseline MoCA scores, there was a significantly greater reduction on anxiety scores in Group 1 (‐0.83±1.3) compared to Group 2 over time (0±0; F(1,9)= 5.3, p=0.047).ConclusionRecruitment is ongoing (total N=30). Only anxiety was associated with poorer cognition at baseline. There were differences between treatment groups on anxiety scores over time, after controlling for baseline MoCA scores. It remains to be seen, after unblinding, whether the group with reduction in anxiety was receiving the primed intervention.